Floating tunable coupler for scalable quantum computing architectures

TL;DR

This paper introduces a floating tunable coupler for quantum processors that enables zero coupling without direct qubit-qubit capacitance, enhancing scalability and reducing residual interactions.

Contribution

The paper presents a novel floating tunable coupler design that achieves zero coupling by engineering qubit-coupler polarity, demonstrated experimentally in symmetric and asymmetric configurations.

Findings

Successfully demonstrated zero coupling regimes in two configurations.

Reduced residual couplings in large-scale quantum architectures.

Flexible design options for scalable quantum processors.

Abstract

We propose a floating tunable coupler that does not rely on direct qubit-qubit coupling capacitances to achieve the zero-coupling condition. We show that the polarity of the qubit-coupler couplings can be engineered to offset the otherwise constant qubit-qubit coupling and attain the zero-coupling condition when the coupler frequency is above or below the qubit frequencies. We experimentally demonstrate these two operating regimes of the tunable coupler by implementing symmetric and asymmetric configurations of the coupler's superconducting pads with respect to the qubits. Such a floating tunable coupler provides flexibility in designing large-scale quantum processors while reducing the always-on residual couplings.